a) Field of the Invention
The present invention relates to gear shift controlling system and method for an automatic transmission. Especially, in the automatic transmission, a plurality of frictional elements are provided and a gear shift is carried out in such a manner that at least a first frictional element is clutched (or engaged) or de-clutched (or released) by supplying or draining (connecting or disconnecting) a working oil for an actuator for the first frictional element with a pressure controller or the working oil of another actuator for a second frictional element is transferred from a release state to a clutched state due to a rise in pressure the working oil of the actuator for at least the first frictional element is supplied and drained (connected and disconnected) to and from the first frictional element to render the first frictional element from a release state to a clutched state due to a rise in pressure of the working oil of the actuator for a pressure controller and a pressure reduction of the working oil of the actuator for a second frictional element by a second controller causes the state of the second frictional element to be transferred from the clutch state to the release state.
b) Description of the Related Art
In the automatic transmission, a plurality of frictional elements such as clutches and brakes are selectively activated to be clutched state under a liquid pressure to determine a power transmission path (gear range) in a gear transmission system. The frictional element to be activated is switched so that a gear shift to another gear range is carried out.
It is well known that with the gear shift control for the automatic transmission, the working oil of the actuator for at least first frictional element is supplied or drained to clutch or de-clutch the first frictional element, or the working oil of the actuator for at least the frictional element is supplied or drained to shift the state of the first frictional element from the released state or clutched state due to the rise in pressure with the pressure controller and the pressure reduction of the working oil of the actuator for the second frictional element causes the second frictional element to be in the released state from the clutched state, and the gear shift from a certain gear range to another gear range is advanced.
It is noted that although the shift control system and method according to the present invention are not limited to an interchange (or clutch-to-clutch) shift of 1 versus 1 (one release element and one clutching element), one example of the interchange shift will be described below to help clarification of the background of the invention.
In this example, in the automatic transmission, the gear shift is carried out by a, s-called, interchange shift (clutch-to-clutch shift) of the frictional element in such a way that while releasing a certain frictional element due to a reduction in a working liquid pressure (pressure reduction in the working oil of the actuator by means of a pressure controller), another frictional element is clutched in response to arise in the working liquid pressure by the pressure controller.
It is noted that the frictional element to be switched from the clutch state to the release state is called a release side frictional element and its working liquid pressure is called a release side working liquid pressure. In addition, the frictional element to be switched from the release state to the clutched state is, called, a release side frictional element, and its working liquid pressure is, called, a clutch side working liquid pressure.
Hence, it is possible to complete the shift with a release-and-clutch control for these frictional elements, while the release side frictional element is released due to the rise in the clutch side working liquid pressure and the clutch side frictional element.
A Japanese Patent Application First Publication No. Heisei 2000-065198 (JP2000065198) published on Mar. 3, 2000 exemplifies a previously proposed a drive down controller. In the drive down controller, a transmission controller prevents a racing after the end of an inertia phase by setting a sum of a capacity of both clutch side and release side frictional elements during the end of shift to a value equal to or larger than an input torque xc3x971.0.
It is noted that the term of xe2x80x9cracingxe2x80x9d or xe2x80x9cracesxe2x80x9d points to a state in which, in a case of a gear ratio in the down shift mode, the gear ratio exceeds a normal gear ratio upon the end of the gear shift and is shifted to a lower gear ratio.
As described above, the racing can be effectively be prevented according to the drive down controller disclosed in the above-described Japanese Patent Application First Publication. However, more further improvements are needed in view of the following respects.
(A) Since, according to the above-described previously proposed drive down gear shift controller, a time at which the inertia phase is ended and predicted and the gradient is determined. If the inertia phase is ended at a prediction time, a target hydraulic is reached when the inertial phase is ended.
Hence, if the end time of the inertia phase is deviated from the prediction time with actual input torque and/or release transmission torque differed from its estimated value, the hydraulic during the end of inertia phase does not become the aimed (target) hydraulic. Consequently, a racing prevention function that the drive down controller has cannot sufficiently be exhibited.
(B) Next, referring to FIGS. 16A and 16B, FIG. 16A shows a case where an actual input torque is larger than that the controller recognizes or a release transmission is smaller than that the controller recognizes (too early (or too fast) in the advance of gear shift) and FIG. 16B shows a case wherein the actual input torque is smaller than that the controller recognizes (too slow (too late) in the advance the gear shift).
In FIGS. 16A and 16B, concerning with the gear ratio, a variation in the actual gear ratio is denoted by a solid line and a variation in a predicted gear ratio is denoted by a broken line. In addition, A denotes the aimed, viz., the target hydraulic at the time of inertia phase end (at the release command pressure side), Axe2x80x2 denotes the aimed, viz., the target hydraulic at the time of the end of inertia phase (clutch command pressure side), B denotes the aimed hydraulic, viz., the target hydraulic at the release command pressure side when the inertia phase is actually ended and Bxe2x80x2 denotes the hydraulic at a side of the clutch command pressure when the inertia phase is actually ended.
In either of the cases shown in FIGS. 16A and 16B, the actual input torque and release transmission torque are different from their estimated values and the end time of the inertia phase is deviated from the predicted time. At this time, the hydraulic at the time of end of inertia phase does not become the aimed one. In the case of FIG. 16A (too early in the advance of the gear shift), each hydraulic B and Bxe2x80x2 at which the actual inertia phase is lowered than the aimed hydraulic A and Axe2x80x2 at the time of ending the inertia phase.
In the case of FIG. 16B, (it is slow in advancing the gear shift) the hydraulic B when the inertia phase is actually ended is in excess of the aimed hydraulic A when the inertia phase is ended. In this way, the hydraulic is not easy to be settled as desired.
Hence, when the advance in the gear shift is too early (FIG. 16A), the release pressure is ended with small release pressure. At this time, there is a great possibility in the occurrence in racing. When the gear shift is slow in advancing the gear shift (FIG. 16B), the release pressure is furthermore raised so that it further becomes difficult to advance the gear shift.
(C) Hence, it is desired to avoid the above-described state by an introduction of new ideas and new techniques and to secure an appropriate gear shift control for the automatic transmission.
It is, hence, an object of the present invention to provide improved gear shift controlling system and method for an automatic transmission which are capable of performing a suitable gear shift by controlling the working oil of actuator for at least the first frictional element through the pressure controller and applying this control of the working oil to the gear shift control from the first gear range to the second gear range.
According to a first aspect of the present invention there is provided with a gear shift controlling apparatus for an automatic transmission, the automatic transmission comprising a plurality of frictional elements and a pressure controller connecting and disconnecting an actuator working liquid pressure for at least a first frictional element from among the frictional elements to make a gear shift from a first gear range to a second gear range, the gear shift controlling apparatus comprising: a pressure controlling section that controls a pressure of the actuator working liquid to vary a torque transmission capacity of the first frictional element; and a torque transmission capacity setting section that sets the torque transmission capacity according to a gear ratio which varies in accordance with a gear shift from the first gear range to the second gear range, during an inertia phase during which the gear shift from the first gear range to the second gear range occurs.
According to a second aspect of the present invention, there is provided a gear shift controlling apparatus for an automatic transmission, the automatic transmission comprising: a plurality of frictional elements; a first pressure controller to raise an actuator working oil pressure of at least a first one of the frictional elements to transfer the actuator working oil from a release state of the first frictional element to a clutch state thereof; and a second pressure controller to reduce an actuator working oil pressure of at least a second one of the frictional elements to transfer the actuator working oil from the clutch state of the second frictional element to the release state thereof, whereby the automatic transmission makes a gear shift from a first gear range to a second gear range, the gear shift controlling apparatus comprising: a first pressure controlling section that controls a first torque transmission capacity for the first frictional element through the first pressure controller; a second pressure controlling section that controls a second torque transmission capacity for the second frictional element through the second pressure controller; and a torque transmission capacity setting section that sets each of the first and second torque transmission capacities according to a gear ratio which varies in accordance with a gear shift from the first gear range to the second gear range, during an inertia phase during which the gear shift from the first gear range to the second gear range occurs.
According to a third aspect of the present invention, there is provided with a gear shift controlling apparatus for an automatic transmission, the automatic transmission comprising a plurality of frictional elements and the automatic transmission being enabled to make a gear shift by a release-to-clutch control in such a manner that while a first one of the frictional elements is released by a decrease pressure control for a working liquid pressure, a second one of the frictional elements is clutched by an increase pressure control for the working liquid pressure, the gear shift controlling apparatus comprising: a release-to-clutch controlling section that controls the working liquid pressure for each of the first and second frictional elements to make the gear shift in the automatic transmission in such a manner that while the first frictional element is released by the decrease pressure control for the working liquid pressure, the second frictional element is clutched by the increase pressure control for the working liquid pressure; and a release capacity setting section that sets a release capacity during an inertia phase during which the gear shift from a first gear range to a second gear range occurs in accordance with an instantaneous gear ratio during the inertia phase so as to output the release capacity set according to the instantaneous gear ratio.
According to a fourth aspect of the present invention, there is provided with a gear shift controlling method for an automatic transmission, the automatic transmission comprising a plurality of frictional elements and a pressure controller connecting and disconnecting an actuator working liquid pressure for at least a first one of the frictional elements to make a gear shift from a first gear range to a second gear range, the gear shift controlling method comprising: controlling a pressure of the actuator working liquid to vary a torque transmission capacity of the first frictional element; and setting the torque transmission capacity according to a gear ratio which varies in accordance with a gear shift from the first gear range to the second gear range, during an inertia phase during which the gear shift from the first gear range to the second gear range occurs.
According to a fifth aspect of the present invention, there is provided with a gear shift controlling method for an automatic transmission, the automatic transmission comprising: a plurality of frictional elements; a first pressure controller to raise an actuator working oil pressure of at least a first one of the frictional elements to-transfer the actuator working oil from a release state of the first frictional element to a clutch state thereof; and a second pressure controller to reduce an actuator working oil pressure of at least a second one of the frictional elements to transfer the actuator working oil from the clutch data of the second frictional element to the release state thereof, whereby the automatic transmission makes a gear shift from a first gear range to a second gear range, the gear shift controlling method comprising: controlling a first torque transmission capacity for the first frictional element through the first pressure controller; controlling a second torque transmission capacity for the second frictional element through the second pressure controller; and setting each of the first and second torque transmission capacities according to a gear ratio which varies in accordance with a gear shift from the first gear range to the second gear range during an inertia phase during which the gear shift from the first gear range to the second gear range occurs.
According to a sixth aspect of the present invention, there is provided with a gear shift controlling method for an automatic transmission, the automatic transmission comprising a plurality of frictional elements and the automatic transmission being enabled to make a gear shift by a release-to-clutch control in such a manner that while a first one of the frictional elements is released by a decrease pressure control for a working liquid pressure, a second one of the frictional elements is clutched by an increase pressure control for the working liquid pressure, the gear shift controlling method comprising: controlling the working liquid pressure for each of the first and second frictional elements to make the gear shift in the automatic transmission in such a manner that while the first frictional element is released by the decrease pressure control for the working liquid pressure, the second frictional element is clutched by the increase pressure control for the working liquid pressure; and setting a release capacity during an inertia phase during which the gear shift from a first gear range to a second gear range occurs in accordance with an instantaneous gear ratio during the inertia phase so as to output the release capacity set according to the instantaneous gear ratio.
This summary of the invention does not necessarily describe all necessary features so that the invention may also be a sub-combination of these described features.
The other objects and features of this invention will become understood from the following description with reference to the accompanying drawings.